Preliminary investigations in our laboratory have led to the discovery of a soluble, cytochrome P-450-dependent, 6-deoxy-erythronolide b hydroxylase in Streptomyces erythreus. This enzyme system will be investigated from two different angles. In the first approach, the individual components of the cytochrome P-450-dependent enzyme system will be resolved and characterized. The fact that this hydroxylase is readily obtained in soluble form, requiring no inducton for its presence, and is produced by a highly developed microorganism points to the unique character of this system. Cytochrome P-450 will be studied to obtain information on its heme content, iron oxidation state, ligand binding, molecular weight and sulfhydryl groups. If a heat stable, lipid fraction, will be found, it will be characterized. The third possible component, NADPH-cytochrome c reductase, will likewise be investigated. When all the components are sufficiently pure, reconstitution experiments will be attempted. The cytochrome P-450-dependent hydroxylase from S. erythreus will be compared to that found in Pseudomono putida, Candida tropicalis, and rat liver microsomes. Such a study will aid in understanding the evolutionary pattern of these cytochromes, as well as provide a better understanding of the general catalytic mechanism of these cytochromes.